Tensioning arrangement for framed flexible materials



July 7, 1959 R. A. KNOWLES TENSIONING ARRANGEMENT FOR FRAMED FLEXIBLE MATERIALS Filed Aug. 26, 1955 2 Sheets-Sheet l JF/G. 3.

Inventor Wlfiwv! ttorney July 7, 1959 R. A. KNOWLES 2,393,162

TENSIONING ARRANGEMENT FOR FRAMED FLEXIBLE MATERIALS Filed Aug. 26, 1955 2 Sheets-Sheet 2 Inventor 831 Home y United States Patent TENSIONING ARRANGEMENT FOR FRAMED FLEXIBLE MATERIALS Reginald Alfred Knowles, Moreton, Wirral, England Application August 26, 1955, Serial No. 530,756

Claims priority, application Great Britain August 31, 1954 2 Claims. (Cl. 45-24) The present invention concerns the stretching of a flexible web, for example a perforate web or mesh suitable for use in screen printing. Such stretching may be either preliminary to the permanent fixing of the stretched web on to a support such as a frame for instance by use of an adhesive; or may be for direct use whilst remaining attached to the stretching device.

According to the present invention a device for stretching a flexible web includes a web gripping means comprising a longitudinally extending member of generally U-section with adjustable web tensioning means attached thereto and adapted to pull the member in the general direction in which the U-limbs extend away from the central region of the U, and a pair of strips conveniently of rectangular section one of which is adapted to be enwrapped by an end region of the web, said strips being preferably of a length commensurate with that of said U-shaped member and of such width and depth as to be capable of being accommodated, together with the enwrapping end region of the web, in the space between said U-limbs.

A web, especially a mesh for screen printing, may be attached to a frame by the use of a stretching device of adjustable size temporarily surrounding a frame and holding the web is an extended condition whilst it is being secured to the frame. The thus pre-stretched web is pref erably attached to the frame by use of a suitable adhesive. After setting of such adhesive the frame with mesh attached is removed from the stretching device, the excess web being cut away.

The stretching device preferably includes four frame members mutually engageable in alternative positions such as by the provision on each member of a plurality of apertures each adapted to receive a projection at the end of one of the adjacent members, whereby to enclose a space of variable size. Each of these members is adapted to receive a plurality of screw tensioning means fixed to a web-engaging means extending parallel to the member.

Alternatively, a web, especially a mesh for screen printing, may be stretched on a frame on which it is subsequently used directly, the frame preferably including an anchorage for the tensioning screw means and presenting an edge adapted to define a free area of tensioned web clear of the stretching device.

With these and other objects in view which will become apparent in the following detailed description, the present invention will be clearly understood in connection with the accompanying drawings, in which:

Figure 1 is a fragmentary perspective view of one form of construction;

Figs. 2 and 3 are details in perspective;

Fig. 4 is a diagrammatic plan showing two alternative arrangements of the members of one stretching device;

Fig. 5 is a detail in section of another form of construction; and

Fig. 6 is a fragmentary perspective view of a preferred 2,893,162 Patented July 7, 1959 form of complete arrangement of stretching device and web, for direct use in screen printing.

Referring now to the drawings and in particular to Figs. 1 to 4, in one form of stretching device especially suitable for applying a stretched web, for instance a mesh for screen printing, to a frame to which the web is then permanently fixed, four wood bars 11, 12, 13 and 14 each have a number of apertures in the form of mortises and one tenon which can fit into one of the mortises of an adjacent bar. Thus the four bars may be assembled (without use of glue or other adhesive) in a variety of ways (two examples of which are illustrated in Fig. 4) so as to fit around a frame to which a mesh is to be applied.

Each bar carries a number of brackets 15, each bracket being fixed to its outer face and presenting a hole through which a tension bolt 16 can pass. Each tensioning bolt is secured to one flange of a metal channel section element 17. Each element 17 lies approximately parallel to the bar to which it is attached.

Each of the four edge regions of the mesh 18 to be stretched is Wrapped around two metal strips 19 and 20 of rectangular section which are then inserted and frictionally engaged in the appropriate channel element 17.

The strips 19 and 20 may be held together at their ends by any suitable means, for example, by the buckle seen in Fig. 2 or by a mushroom headed rivet at each end of one strip engaging in an open ended slot in each end of the other. Thereafter stretching is effected by rotation of wing nuts 21 on the bolts 16.

The stretched mesh is secured by adhesive to one face of a simple frame disposed within the rectangular space defined by the four bars 11, 12, 13 and 14. After the adhesive has set the mesh may be trimmed flush with the outer edges of the frame and the stretching device may then be removed.

It will be evident that the stretching device may itself be used as the frame for a mesh; for printing purposes, as a printing frame. To enable the mesh framed by the stretching device to be laid flush on a flat surface, the mesh is arranged to pass from the edges held in the elements 17 over the edges of attached flanges 21' (Fig. 5) extending along the four bars and standing out sufficiently therefrom to maintain the free area of the mesh in a plane clear of the stretching device. It is convenient in this respect to provide a channel 22 (Fig. 6) on each of the four bars with the bolts 16 screwed through one flange of the channel 22, the other flange then presenting the edge referred to while the mesh-engaging means are accommodated within the section of the channel 22.

In its application to screen printing, the invention enables a plurality of small frames having mesh secured thereto in a stretched and usable state merely by adhesive. These smaller or insert frames may be held in position in a master frame by bars or other elements of appropriate cross section. The invention also enables stencil designs to be stored economically in screen form for future use. Moreover the production of a highly stretched screen, such as is required for trichromatic printing, is readily effected by the use of an arrangement in accordance with the invention.

An important advantage to be derived from the invention is found in the considerable amount of time saved in applying the web in a stretched condition and in the possibility of subsequent simple retightening or tension adjustment after the stretched web has been in use.

While I have disclosed a plurality of embodiments, it is to be understood that these embodiments are given by example only and not in a limiting sense, the scope of the present invention being determined by the objects and the claims.

I claim:

1. A device for stretching a flexible material comprising a rectangular frame work constructed of four frame work members, each member having a projection at one of its ends thereof, said four frame work members being engageable together in a plurality of selected positions by means of a plurality of apertures in said frame work members each adapted to receive the projection at the end of an adjacent member whereby to enclose a space of variable size, four longitudinally extending members of U-section in said frame work, adjustable web tensioning means attached to said U-members in said frame work, said web tensioning means being adapted to pull said members in the direction in which the limbs of the U extend and four pairs of rectangular strips, one strip of 15 2. A method of making a screen for screen printing by means of a stretching device including a web gripping means comprising a longitudinally extending member of generally U-section with adjustable web tensioning means attached thereto, comprising the steps of pulling said member in the general direction in which the U-limbs extend away from the central region of the U, and enwrapping an end region of each edge portion of said Web on a complementary strip, and accommodating said strips together with said enwrapping end region of said web in the space between said U-limbs.

References Cited in the file of this patent UNITED STATES PATENTS 333,737 Fougeadoire Jan. 5, 1886 1,799,029 Smith Mar. 31, 1931 FOREIGN PATENTS 260,896 Germany June 10, 1913 

